Synopsis

Johann arrives at Berk and the Riders are already expecting his arrival, but Snotlout states that he doesn't let him touch any of his goods because the last time Trader Johann was at Berk, Snotlout broke half of his cool stuff. While the Riders are enjoying their time looking around Johann's ship, Gobber finds mass quantities of scrap metal on board and decides to take it to his workshop. Snotlout, again, breaks some of Johann's goods. The Riders (except Snotlout) helps Gobber's scrap metal to be delivered to his workshop, meanwhile Toothless is somewhat suspicious and cautious to the scrap metal.

Grieving Macey

At nightfall, an unknown thick fog travels and explores the village and targets Gobber's scrap metal. In the morning, some of the town's metal has been stolen including Tuffnut's mace, which he has named 'Macey', that he bought from Trader Johann and is miserable without it. Hiccup and Astrid starts their investigation by looking at Gobber's workshop, and they find no footprints or clues for the metal thief, even though Gobber has set several booby traps around his workshop, that he accidentally set it on. Next, they investigate at the Twins' house where they find Tuffnut's shrine for Macey, but still, they find no clues or footprints in the location, but Tuffnut still suspects that Ruffnut stole it. Hiccup and Astrid decide that they continue their investigation tomorrow.

Late at night, the unknown thick fog travels through Berk again, stealing all the town's metal. As the fog enters through Hiccup and Stoick'shouse, they steal metal along their way up to Hiccup's room. Toothless wakes up and witnesses the fog, while Hiccup gets lifted and the fog tries to take his metal leg. Toothless pulls Hiccup away from the fog, blows the fog away by using his wings, and reveals that the metal thief is actually Smothering Smokebreaths. Before they make their exit, they steal some of Hiccup's metal things, although unable to grab his helmet, and the Smokebreaths escape the room.

At dawn, most of the town's metal is now stolen including the Riders' Viking helmets. Hiccup informs them that the thief is actually Smothering Smokebreath dragons, but it is still unclear of how and why the Smokebreaths got to Berk, as they are excluded in Breakneck Bog. Gobber interrupts and shouts that the Smokebreaths stole his scrap metal from Trader Johann. Hiccup suddenly suspects Trader Johann.

At the Great Hall, Hiccup and Stoick ask Johann where he got the vast quantities of scrap metal. Johann reveals that he got the scrap metal from a Berserker at a great price, and made the deal in Breakneck Bog. Hiccup tells Johann that the scrap metal he got was from a Smokebreath nest filled with hatchlings. Stoick and Hiccup leave in anger, including Toothless who interrupts his snack. Stoick and Hiccup watch the villagers struggling to continue their daily lives, as most of their things are now made of wood unable to support most of the weight, even worst Gobber informs that almost all of the town's metal is depleted and the Armory is lacking weaponry, making Berk mostly vulnerable for an invasion. Hiccup and the Riders must find the missing metal before an invasion by Dagur is settled. Fishlegs tells that the Smothering Smokebreaths can't be far due to carrying all the metal weight. Hiccup suggests that the Smokebreaths built a nest at Berk. But they don't have enough time to find their nest, so Hiccup suggests they lure it by gathering all the last drops of metal resources in Berk and let them steal it, and then follow them to where they brought it. Snotlout is forced to give his spare metal helmet.

The Smothering Smokebreaths took the bait, and the Riders wait for the perfect time to jump in but the Twins quickly execute the plan by attacking the seemingly Smokebreaths still at the area, only later to be revealed they are attacking themselves. The Smokebreaths' cover splits into two, forcing the Riders to split up. Hiccup and Toothless follows one, almost losing it, but manage to find another batch of them. They struggle as the Smokebreaths begin to corner them and wants to take their metal. A Smokebreath manages to grab Toothless' metal rod, making him unable to fly and gently crashes down. They are forced to follow the Smokebreaths on foot. Hiccup and Toothless close in, and Hiccup uses his shield to catch the Smokebreath that took the rod, but proves stronger than him and drags him along the way on the ground. The Smokebreath gives up the rod and the rope that's pulling him breaks apart. Hiccup and Toothless stumble to the location of the Smokebreaths' new nest.

Astrid informing Hiccup of the Berserker and Outcast invasion

Astrid finds Hiccup and informs him that a large-scale Berserker and Outcast invasion is sailing toward Berk's territory.

It is revealed that Dagur and Savage planned to offer the stolen scrap metal filled with hatchlings to Trader Johann, and later make Berk mostly vulnerable. Hiccup comes up with a plan, thanks to Tuffnut, and orders the villagers to give their last spare of metal and gather it, Gobber volunteers to give to Hiccup his arm-weapon that he took his first Outcast with, and tells Hiccup to take good care of it. The Riders lure the Smothering Smokebreaths away from their nest by using the last metal resources of Berk. Dagur was getting impatient that no movement or attack was coming in their way. When they finally arrive, they arm themselves with weapons to prepare for the attack. Stoick and the other Vikings make their last stand, while the Riders close in the fleet so that the thick fog made sure Dagur's armada was unable to see the Berk mainland and unable to fire any target. The Riders drop their metal load, leaving Dagur to wonder why they were dropping spoons. As planned, dozens of Smokebreaths attack their fleet and steal all their metal. They are unable to attack the Smokebreaths, and within minutes, the entire fleet is left without metal support and their ships begin to completely disassemble. The Berserkers are forced to retreat, and while Dagur threatens that it wasn't over, two Smothering Smokebreaths steal his helmet and kneecap.

Dagur getting his helmet stolen by two Smokebreaths

Hours later, The Riders are able to return most of the town's metal, including Macey, and Tuffnut was very glad to see it. Stoick asks Hiccup of how he plans to drive the Smokebreaths away from Berk, and Hiccup responds, saying that he planned to put the scrap metal bait on Trader Johann's ship in an attempt to lure away the Smokebreaths. Johann heads for Breakneck Bog, struggling to keep the Smokebreaths off of his ship. Hiccup and Toothless watch on and escort him to the island.

Errors

If Hiccup and Toothless were making so much noise when the Smokebreaths tried to steal the metal from his house (including Hiccup's leg) Stoick would've heard them, because his bedroom is just downstairs.